[mips][msa] Correct definition order of ftrunc_[su], ftint_[su], and ftq.

Define these three instructions in alphabetical order (like the rest of the
file).
No functional change.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192880 91177308-0d34-0410-b5e6-96231b3b80d8